In a world threatened by a demon-filled dimension called "Mato," humanity finds hope in a special type of "peach" tree that grants powers to those who consume its fruit. However, these powers only work for women. As a result, women gain higher social status while men struggle as second-class citizens. Enter Yuuki Wakura, a resourceful high school senior whose sister vanished during a Mato incident five years ago. While facing the harsh reality of his future, Yuuki finds himself trapped in the Mato dimension.
He's rescued from demons by Captain Kyouka Uzen of the Anti-Demon Corps, who grants him powers as her "slave." This transforms him into a powerful beast mount that fights off demons. However, there's an unexpected cost to being her "slave" — and it's not Yuuki who bears the burden.